Field of the Invention
The present invention relates to a communication technology for transmitting content data.
Description of the Related Art
In recent years, a stream distribution system that distributes, to users, content in streaming format including audio data and video data has been provided. In such a system, the users can view desired content such as live content during image capture, and recorded content, for example, a movie, by receiving the content with the users' own terminal apparatuses via a network.
Streaming technologies using HTTP (HyperText Transfer Protocol) (for example, MPEG-DASH) are known as technologies that enable streaming distribution via an open network such as the Internet. In these HTTP streaming technologies, content data is divided into units of several seconds, called segments, on the server side. A URL (Uniform Resource Locator) being access information to each segment is described in a playlist. The playlist is received by a playback apparatus. The access information in the playlist is used to acquire a desired segment. Accordingly, pseudo streaming is realized.
HTTP streaming used in a VoD (Video on Demand) system and the like requires to distribute multiple pieces of content data to multiple playback apparatuses. In order to handle this, original content data is generally transferred to, for example, a plurality of servers existing on the cloud to distribute processing load with a load balancer.
On the other hand, real-time content streaming places prime importance on the real-time property of content. Accordingly, it is required to deliver content acquired by image capture or the like to a playback apparatus with latency as low as possible. It is required to reduce the time from the acquisition of content data on the server side to the distribution of the content data to the playback apparatus side to distribute the content with low latency.
In a distribution system described in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276, a playback apparatus acquires a playlist from a server, accesses URIs (Uniform Resource Identifiers) of a plurality of content files described in the playlist in turn, and acquires the contents.
However, a case is conceivable which takes a long time from the input of content data to a communication apparatus to the acquisition of the content data by a communication partner of the communication apparatus.
For example, let's take, as an example, a case where content data (a segment) is acquired on a server side (communication apparatus side) to describe, in a playlist, a URL for requesting the content data. In this case, the server transmits the playlist to a client. The client, which has parsed the playlist, transmits a request for the content data to the server. The server, which has received the request, transmits the content data to the client. In this manner, the client can play back the content data. However, when the server transmits the content data to a playback apparatus following the above procedure, it is conceivable to take a long time from the acquisition of the segment by the server to the acquisition of the content data by the playback apparatus.